Several challenges face patients and physicians in the area of drug delivery. Examples of challenging areas of drug delivery include ocular drug delivery, subcutaneous drug delivery, and sustained release of the drug to be delivered. Many current therapies require repetitive treatments, such as multiple injections, multiple topical applications, or multiple series of eye drops per day. Other drug delivery systems, such as topically applied medications, can have a peak effect within a few hours. Repeated treatments are then also required for these delivery systems. The repetitive nature of these treatments often results in reduced efficacy because of poor patient compliance. The lack of patient compliance and the associated economic costs of repeated treatments can thus lead to ineffective treatments, further medical complications, and deterioration of the patient's health. Premature depletion and/or release of a drug from an implant or depot can result in undesired initial burst and thereafter insufficient drug being delivered for a portion of the treatment period. Accordingly, there is a need for improved drug delivery systems, such as improved drug depots or implants, that overcome one or more of the shortcomings of current commercial drug delivery systems discussed above.